Soft Robotic Manipulators Inspired by the Fin Ray Effect

Abstract: As robots become increasingly ingrained in our lives, we need to find ways to ensure that these robots are safe for human interaction. In this dissertation, I present two soft robotic manipulators: The Tufts Active Gripper (TAG) and the Tufts Passive Gripper (TPG). Both grippers are predominantly soft and inspired by the Fin Ray Effect, a structure based on the deformation of fish fins. ... read moreIt was discovered that modifying the angle of the crossbeams of the Fin Ray geometry with respect to the base resulted in a preferred bending direction. This angle was optimized through FEA analysis and a set of equations to describe the Fin Ray Effect were developed. This optimization was used in the final designs of TAG, an active gripper that requires power to maintain grip on an object, and TPG, a passive gripper inspired by the Manduca sexta that requires power to open and close but not to maintain grip. TAG and TPG are both 3D printed as one part, require under 5 steps to attach their motor/tendon actuation systems, and can both be produced and outfitted with electronics for under $200. The load capacity of TAG and TPG were tested. Both can hold approximately 550 g in a vertical orientation, but TAG can hold twice as much as TPG in the horizontal orientation (390 g vs 240 g, respectively). This discrepancy is likely due to differences in the designs that were necessary to make a passive gripper, for example a smaller number of supports in the TPG that were meant to prevent unwanted deformation. The TAG and TPG also exerted normal forces differently, with the highest normal forces for TAG at the tip and base and the highest for TPG in the middle. TAG and TPG were both capable of holding a wide range of objects, but it was easiest to hold cylindrical objects and hardest to hold long, thin objects. Future versions of both grippers should improve load capacity and reduce failure. read less